Virtual Router to Support Multicast

##### ISSUE TYPE

* Improvement Request

##### COMPONENT NAME

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Virtual Router
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##### CLOUDSTACK VERSION

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4.19.1.1
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##### CONFIGURATION

##### OS / ENVIRONMENT

##### SUMMARY

Currently Cloudstack Virtual Router doesnt support Multicast from external networks (eg. Private Gateway).

In our case, our customers require multicast support because they decode Stock Market Feeds from the Stock Exchange. And Majority Stock Exchange distributes market feeds in ITCH format, which is Multicast.

In order to overcome this limitation now, we had to resort to VNF + L2 Networks.

I also have a curious question, if Cloudstack VR does not support multicast, then why is there a UDP Protocol option in the Network ACL Rules?

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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For VR to support multicast natively
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##### ACTUAL RESULTS

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VR does not support multicast at the moment.
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La issue identifica il Virtual Router di CloudStack e richiede il supporto nativo al multicast per le reti esterne, ma non indica file, test, comandi o punti di ingresso. Inizia individuando l'implementazione di rete del Virtual Router e i test esistenti dei protocolli o del routing. Il lavoro è completato quando il traffico multicast funziona nativamente attraverso il Virtual Router per il caso d'uso descritto delle reti esterne.

Scritto dal modello di indicizzazione a partire dal testo della issue.